cp/

	* parser.c (cp_parser_member_declaration): Parse attributes before
	colon of a bitfield in addition to after colon.
testsuite/
	* g++.dg/ext/bitfield7.C: New test.
	* g++.dg/ext/bitfield8.C: New test.
	* g++.dg/ext/bitfield9.C: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@253281 138bc75d-0d04-0410-961f-82ee72b054a4

6 files changed, 85 insertions, 11 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 6a4d28315e9..95110b87c3c 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,8 @@
 2017-09-29  Jakub Jelinek  <jakub@redhat.com>
 
+	* parser.c (cp_parser_member_declaration): Parse attributes before
+	colon of a bitfield in addition to after colon.
+
 	* Make-lang.in (check-c++-all): Test also c++2a.
 
 2017-09-28  Jason Merrill  <jason@redhat.com>
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index f22c2c091dc..71c27a40ce2 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -23445,35 +23445,68 @@ cp_parser_member_declaration (cp_parser* parser)
 	{
 	  tree attributes = NULL_TREE;
 	  tree first_attribute;
+	  bool is_bitfld = false;
+	  bool named_bitfld = false;
 
 	  /* Peek at the next token.  */
 	  token = cp_lexer_peek_token (parser->lexer);
 
+	  /* The following code wants to know early if it is a bit-field
+	     or some other declaration.  Attributes can appear before
+	     the `:' token, but are hopefully rare enough that the
+	     simplicity of the tentative lookup pays off.  */
+	  if (cp_next_tokens_can_be_attribute_p (parser)
+	      || (token->type == CPP_NAME
+		  && cp_nth_tokens_can_be_attribute_p (parser, 2)
+		  && (named_bitfld = true)))
+	    {
+	      cp_parser_parse_tentatively (parser);
+	      if (named_bitfld)
+		cp_lexer_consume_token (parser->lexer);
+	      cp_parser_attributes_opt (parser);
+	      token = cp_lexer_peek_token (parser->lexer);
+	      is_bitfld = cp_lexer_next_token_is (parser->lexer, CPP_COLON);
+	      cp_parser_abort_tentative_parse (parser);
+	    }
+
 	  /* Check for a bitfield declaration.  */
-	  if (token->type == CPP_COLON
+	  if (is_bitfld
+	      || token->type == CPP_COLON
 	      || (token->type == CPP_NAME
-		  && cp_lexer_peek_nth_token (parser->lexer, 2)->type
-		  == CPP_COLON))
+		  && cp_lexer_nth_token_is (parser->lexer, 2, CPP_COLON)
+		  && (named_bitfld = true)))
 	    {
 	      tree identifier;
 	      tree width;
+	      tree late_attributes = NULL_TREE;
 
-	      /* Get the name of the bitfield.  Note that we cannot just
-		 check TOKEN here because it may have been invalidated by
-		 the call to cp_lexer_peek_nth_token above.  */
-	      if (cp_lexer_peek_token (parser->lexer)->type != CPP_COLON)
+	      if (named_bitfld)
 		identifier = cp_parser_identifier (parser);
 	      else
 		identifier = NULL_TREE;
 
+	      /* Look for attributes that apply to the bitfield.  */
+	      attributes = cp_parser_attributes_opt (parser);
+
 	      /* Consume the `:' token.  */
 	      cp_lexer_consume_token (parser->lexer);
+
 	      /* Get the width of the bitfield.  */
-	      width
-		= cp_parser_constant_expression (parser);
+	      width = cp_parser_constant_expression (parser);
+
+	      /* Look for attributes that apply to the bitfield after
+		 the `:' token and width.  This is where GCC used to
+		 parse attributes in the past, pedwarn if there is
+		 a std attribute.  */
+	      if (cp_next_tokens_can_be_std_attribute_p (parser))
+		pedwarn (input_location, OPT_Wpedantic,
+			 "ISO C++ allows bit-field attributes only before "
+			 "the %<:%> token");
+
+	      late_attributes = cp_parser_attributes_opt (parser);
+
+	      attributes = chainon (attributes, late_attributes);
 
-	      /* Look for attributes that apply to the bitfield.  */
-	      attributes = cp_parser_attributes_opt (parser);
 	      /* Remember which attributes are prefix attributes and
 		 which are not.  */
 	      first_attribute = attributes;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e0eade336b3..0d637c8deab 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 2017-09-29  Jakub Jelinek  <jakub@redhat.com>
 
+	* g++.dg/ext/bitfield7.C: New test.
+	* g++.dg/ext/bitfield8.C: New test.
+	* g++.dg/ext/bitfield9.C: New test.
+
 	PR c/82340
 	* gcc.dg/tree-ssa/pr82340.c: New test.
 
diff --git a/gcc/testsuite/g++.dg/ext/bitfield7.C b/gcc/testsuite/g++.dg/ext/bitfield7.C
new file mode 100644
index 00000000000..4efc9bf2d04
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/bitfield7.C
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "" } */
+/* { dg-options "-Wno-packed-bitfield-compat -mno-ms-bitfields" { target { i?86-*-mingw* x86_64-*-mingw* } } } */
+
+struct t /* { dg-message "note: offset of packed bit-field 't::b' has changed in GCC 4.4" "" { target pcc_bitfield_type_matters } } */
+{
+  char a:4;
+  char b __attribute__ ((packed)) : 8;
+  char c:4;
+};
+
+int assrt[sizeof (struct t) == 2 ? 1 : -1];
diff --git a/gcc/testsuite/g++.dg/ext/bitfield8.C b/gcc/testsuite/g++.dg/ext/bitfield8.C
new file mode 100644
index 00000000000..688b28988f5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/bitfield8.C
@@ -0,0 +1,12 @@
+/* { dg-do compile { target c++11 } } */
+/* { dg-options "" } */
+/* { dg-options "-Wno-packed-bitfield-compat -mno-ms-bitfields" { target { i?86-*-mingw* x86_64-*-mingw* } } } */
+
+struct t /* { dg-message "note: offset of packed bit-field 't::b' has changed in GCC 4.4" "" { target pcc_bitfield_type_matters } } */
+{
+  char a:4;
+  char b [[gnu::packed]] : 8;
+  char c:4;
+};
+
+int assrt[sizeof (struct t) == 2 ? 1 : -1];
diff --git a/gcc/testsuite/g++.dg/ext/bitfield9.C b/gcc/testsuite/g++.dg/ext/bitfield9.C
new file mode 100644
index 00000000000..4a4ebf23c1f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/bitfield9.C
@@ -0,0 +1,10 @@
+// { dg-do compile { target c++11 } }
+// { dg-options "-pedantic" }
+
+struct S
+{
+  char a:4;
+  char b:8 alignas(int);	// { dg-warning "ISO C\\+\\+ allows bit-field attributes only before the ':' token" }
+  char c:8 [[gnu::aligned(8)]];	// { dg-warning "ISO C\\+\\+ allows bit-field attributes only before the ':' token" }
+				// { dg-error "two consecutive '\\\[' shall only introduce an attribute before '\\\[' token" "" { target *-*-* } .-1 }
+};